Scalable frequency band operation in wireless communication systems

ABSTRACT

To support mobile stations that are not capable of demodulating the entire bandwidth or that can be made to demodulate less than the entire bandwidth, a system, apparatus and method are provided to schedule users on less than all of the bandwidth. Further, certain users can be scheduled on more of the bandwidth than others.

CLAIM OF PRIORITY UNDER 35 U.S.C. §120

The present application for patent is a continuation of patentapplication Ser. No. 11/261,805, filed Oct. 27, 2005, entitled,“SCALABLE FREQUENCY BAND OPERATION IN WIRELESS COMMUNICATION SYSTEMS”,currently pending, and assigned to the assignee hereof and herebyexpressly incorporated by reference herein.

CROSS-REFERENCE TO RELATED APPLICATIONS FOR PATENT

The present Application for Patent is related to the following U.S.patent applications:

-   “A METHOD AND APPARATUS FOR BOOTSTRAPPING INFORMATION IN A    COMMUNICATION SYSTEM” having U.S. application Ser. No. 11/261,065,    filed on Oct. 27, 2005, assigned to the assignee hereof, and    expressly incorporated by reference herein; and-   “Puncturing Signaling Channel For A Wireless Communication System”    having U.S. application Ser. No. 11/260,931 (now U.S. Pat. No.    8,565,194), filed on Oct. 27, 2005, assigned to the assignee hereof,    and expressly incorporated by reference herein; and-   “SYSTEMS AND METHODS FOR Control Channel Signaling” having U.S.    application Ser. No. 11/261,836, filed on Oct. 27, 2005, assigned to    the assignee hereof, and expressly incorporated by reference herein;    and-   “Varied Signaling Channels For A Reverse Link In A Wireless    Communication System” having U.S. application Ser. No. 11/261,806,    filed on Oct. 27, 2005, assigned to the assignee hereof, and    expressly incorporated by reference herein; and-   “Varied Transmission Time Intervals For Wireless Communication    System” having U.S. application Ser. No. 11/260,932, filed on Oct.    27, 2005, assigned to the assignee hereof, and expressly    incorporated by reference herein; and-   “Channel Sensitive Scheduling” having U.S. application Ser. No.    11/260,924, filed on Oct. 27, 2005, assigned to the assignee hereof,    and expressly incorporated by reference herein; and-   “Method And Apparatus For Providing Antenna Diversity In A Wireless    Communication System” having U.S. application Ser. No. 11/261,823,    filed on Oct. 27, 2005, assigned to the assignee hereof, and    expressly incorporated by reference herein; and-   “Mobile Wireless Access System” having U.S. Provisional Application    No. 60/731,013, filed on Oct. 27, 2005, assigned to the assignee    hereof, and expressly incorporated by reference herein; and-   “Variable Shared Signaling Channel” having U.S. application Ser. No.    11/261,158, filed on Oct. 27, 2005, assigned to the assignee hereof,    and expressly incorporated by reference herein.

BACKGROUND

I. Field

The present disclosure relates generally to wireless communications, andamongst other things to scalable frequency band operation.

II. Background

Wireless communication systems have become a prevalent means by which amajority of people worldwide have come to communicate. Wirelesscommunication devices have become smaller and more powerful in order tomeet consumer needs and to improve portability and convenience. Theincrease in processing power in mobile devices such as cellulartelephones has lead to an increase in demands on wireless networktransmission systems. Such systems typically are not as easily updatedas the cellular devices that communicate there over. As mobile devicecapabilities expand, it can be difficult to maintain an older wirelessnetwork system in a manner that facilitates fully exploiting new andimproved wireless device capabilities.

Wireless communication systems generally utilize different approaches togenerate transmission resources in the form of channels. These systemsmay be code division multiplexing (CDM) systems, frequency divisionmultiplexing (FDM) systems, and time division multiplexing (TDM)systems. One commonly utilized variant of FDM is orthogonal frequencydivision multiplexing (OFDM) that effectively partitions the overallsystem bandwidth into multiple orthogonal subcarriers. These subcarriersmay also be referred to as tones, bins, and frequency channels. Eachsubcarrier can be modulated with data. With time division basedtechniques, a each subcarrier can comprise a portion of sequential timeslices or time slots. Each user may be provided with a one or more timeslot and subcarrier combinations for transmitting and receivinginformation in a defined burst period or frame. The hopping schemes maygenerally be a symbol rate hopping scheme or a block hopping scheme.

Code division based techniques typically transmit data over a number offrequencies available at any time in a range. In general, data isdigitized and spread over available bandwidth, wherein multiple userscan be overlaid on the channel and respective users can be assigned aunique sequence code. Users can transmit in the same wide-band chunk ofspectrum, wherein each user's signal is spread over the entire bandwidthby its respective unique spreading code. This technique can provide forsharing, wherein one or more users can concurrently transmit andreceive. Such sharing can be achieved through spread spectrum digitalmodulation, wherein a user's stream of bits is encoded and spread acrossa very wide channel in a pseudo-random fashion. The receiver is designedto recognize the associated unique sequence code and undo therandomization in order to collect the bits for a particular user in acoherent manner.

A typical wireless communication network (e.g., employing frequency,time, and/or code division techniques) includes one or more basestations that provide a coverage area and one or more mobile (e.g.,wireless) terminals that can transmit and receive data within thecoverage area. A typical base station can simultaneously transmitmultiple data streams for broadcast, multicast, and/or unicast services,wherein a data stream is a stream of data that can be of independentreception interest to a mobile terminal. A mobile terminal within thecoverage area of that base station can be interested in receiving one,more than one or all the data streams transmitted from the base station.Likewise, a mobile terminal can transmit data to the base station oranother mobile terminal. In these systems the bandwidth and other systemresources are assigned utilizing a scheduler.

For the case of large deployment bandwidths, it is desirable to supportmobile stations that are not capable of demodulating the entirebandwidth or that can be made to demodulate less than the entirebandwidth.

SUMMARY

The following presents a simplified summary of one or more embodimentsin order to provide a basic understanding of such embodiments. Thissummary is not an extensive overview of all contemplated embodiments,and is intended to neither identify key or critical elements of allembodiments nor delineate the scope of any or all embodiments. Its solepurpose is to present some concepts of one or more embodiments in asimplified form as a prelude to the more detailed description that ispresented later.

In an aspect, a wireless communication apparatus comprises a processorconfigured to instruct transmission of a plurality of control channeltransmissions on each of a plurality of carriers. The control channeltransmissions include sufficient information to communicate within thecarrier without utilizing information contained in any other of theplurality of the control channels.

In another aspect, method comprises transmitting on a first carrier acontrol channel transmission and transmitting on second carrier anothercontrol channel transmission during a substantially same time frame asthe control channel transmission. The control channel transmissionscontain sufficient information to communicate within the carrier withoututilizing information contained in any other of the plurality of thecontrol channels.

Various means and computer readable media may be utilized to perform theabove described methods and processor configured functions.

To the accomplishment of the foregoing and related ends, the one or moreembodiments comprise the features hereinafter fully described andparticularly pointed out in the claims. The following description andthe annexed drawings set forth in detail certain illustrative aspects ofthe one or more embodiments. These aspects are indicative, however, ofbut a few of the various ways in which the principles of variousembodiments may be employed and the described embodiments are intendedto include all such aspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates aspects of a multiple access wireless communicationsystem.

FIGS. 2A and 2B illustrate aspects of superframe structures for amultiple access wireless communication system.

FIG. 3 illustrates aspects of multi-carrier frame structures for amultiple access wireless communication system.

FIG. 4A illustrates aspects of a forward link frame of a carrier for amultiple access wireless communication system.

FIG. 4B illustrates aspects of a reverse link frame of a carrier for amultiple access wireless communication system

FIG. 5 illustrates aspects of a method of scheduling users in amulti-carrier system.

FIG. 6 illustrates aspects of a method of accessing and communicating ina wireless communication system.

FIG. 7 illustrates aspects of a transmitter and receiver in a multipleaccess wireless communication system.

DETAILED DESCRIPTION

Various embodiments are now described with reference to the drawings,wherein like reference numerals are used to refer to like elementsthroughout. In the following description, for purposes of explanation,numerous specific details are set forth in order to provide a thoroughunderstanding of one or more embodiments. It may be evident, however,that such embodiment(s) may be practiced without these specific details.In other instances, well-known structures and devices are shown in blockdiagram form in order to facilitate describing one or more embodiments.

Referring to FIG. 1, a multiple access wireless communication systemaccording to one embodiment is illustrated. A multiple access wirelesscommunication system 100 includes multiple cells, e.g. cells 102, 104,and 106. In the embodiment of FIG. 1, each cell 102, 104, and 106 mayinclude an access point 150 that includes multiple sectors. The multiplesectors are formed by groups of antennas each responsible forcommunication with access terminals in a portion of the cell. In cell102, antenna groups 112, 114, and 116 each correspond to a differentsector. In cell 104, antenna groups 118, 120, and 122 each correspond toa different sector. In cell 106, antenna groups 124, 126, and 128 eachcorrespond to a different sector.

Each cell includes several access terminals which are in communicationwith one or more sectors of each access point. For example, accessterminals 130 and 132 are in communication base 142, access terminals134 and 136 are in communication with access point 144, and accessterminals 138 and 140 are in communication with access point 146.

Controller 130 is coupled to each of the cells 102, 104, and 106.Controller 130 may contain one or more connections to multiple networks,e.g. the Internet, other packet based networks, or circuit switchedvoice networks that provide information to, and from, the accessterminals in communication with the cells of the multiple accesswireless communication system 100. The controller 130 includes, or iscoupled with, a scheduler that schedules transmission from and to accessterminals. In other embodiments, the scheduler may reside in eachindividual cell, each sector of a cell, or a combination thereof.

Each of the sectors can operate utilizing one or more of a plurality ofcarriers. Each carrier is a portion of a larger bandwidth in which thesystem can operate, or is available for communication. A single sectorutilizing one or more carriers may have multiple access terminalsscheduled on each of the different carriers during any given timeinterval, e.g. frame or superframe. Further, one or more accessterminals may be scheduled on multiple carriers simultaneously.

An access terminal may be scheduled in one carrier or more than onecarrier according to its capabilities. These capabilities may be part ofthe session information that is generated when the access terminalattempts to acquire communication or that has been negotiatedpreviously, may be part of the identification information that istransmitted by the access terminal, or be established according to anyother approach. In certain aspects, the session information may comprisea session identification token that is generated by querying the accessterminal or determining its capabilities through its transmissions.

As used herein, an access point may be a fixed station used forcommunicating with the terminals and may also be referred to as, andinclude some or all the functionality of, a base station, a Node B, orsome other terminology. An access terminal may also be referred to as,and include some or all the functionality of, a user equipment (UE), awireless communication device, terminal, a mobile station or some otherterminology.

It should be noted that while FIG. 1, depicts physical sectors, i.e.having different antenna groups for different sectors, other approachesmay be utilized. For example, utilizing multiple fixed “beams” that eachcover different areas of the cell in frequency space may be utilized inlieu of, or in combination with physical sectors. Such an approach isdepicted and disclosed in copending U.S. patent application Ser. No.11/260,895, entitled “Adaptive Sectorization In Cellular System,” andfiled on even date herewith.

Referring to FIGS. 2A and 2B, aspects of superframe structures for amultiple access wireless communication system are illustrated. FIG. 2Aillustrates aspects of superframe structures for a frequency divisionduplexed (FDD) multiple access wireless communication system, while FIG.2B illustrates aspects of superframe structures for a time divisionduplexed (TDD) multiple access wireless communication system. Thesuperframe preamble may be transmitted separately for each carrier ormay span all of the carriers of the sector.

In both FIGS. 2A and 2B, the forward link transmission is divided intounits of superframes. A superframe may consist of a superframe preamblefollowed by a series of frames. In an FDD system, the reverse link andthe forward link transmission may occupy different frequency bandwidthsso that transmissions on the links do not, or for the most part do not,overlap on any frequency subcarriers. In a TDD system, N forward linkframes and M reverse link frames define the number of sequential forwardlink and reverse link frames that may be continuously transmitted priorto allowing transmission of the opposite type of frame. It should benoted that the number of N and M may be vary within a given superframeor between superframes.

In both FDD and TDD systems each superframe may comprise a superframepreamble. In certain embodiments, the superframe preamble includes apilot channel that includes pilots that may be used for channelestimation by access terminals, a broadcast channel that includesconfiguration information that the access terminal may utilize todemodulate the information contained in the forward link frame. Furtheracquisition information such as timing and other information sufficientfor an access terminal to communicate on one of the carriers and basicpower control or offset information may also be included in thesuperframe preamble. In other cases, only some of the above and/or otherinformation may be included in this superframe preamble.

As shown in FIGS. 2A and 2B, the superframe preamble is followed by asequence of frames. Each frame may consist of a same or a differentnumber of OFDM symbols, which may constitute a number of subcarriersthat may simultaneously utilized for transmission over some definedperiod. Further, each frame may operate according to a symbol ratehopping mode, where one or more non-contiguous OFDM symbols are assignedto a user on a forward link or reverse link, or a block hopping mode,where users hop within a block of OFDM symbols. The actual blocks orOFDM symbols may or may not hop between frames.

Referring to FIG. 3, aspects of a channel structure for a multipleaccess wireless communication system are illustrated. A bandwidth 300 isavailable for communication according to system design parameters. Thebandwidth 300 comprises a number of carriers 302. Each carrier includesone or more forward link frames 304 and reverse link frames 308, each ofwhich may be part of one or more superframes as discussed with respectto FIG. 2.

Each forward link frame 304 of each carrier 302 includes controlchannels 306. Each of the control channels 306 may include informationfor functions related to, for example, acquisition; acknowledgements;forward link assignments for each access terminal, which may bedifferent or the same for broadcast, multicast, and unicast messagetypes, reverse link assignments for each access terminal; reverse linkpower control for each access terminal; and reverse linkacknowledgements. It should be noted that more or fewer of suchfunctions may be supported in control channels 306 of one or all of thecarriers. Also, the control channels 306 may hop in each frame accordingto hopping sequences that are the same or different from hoppingsequences assigned to data channels.

Each reverse link frame 308 includes a number of reverse linktransmissions, e.g. 312, 314, 316, 318, 320, 322, 324, 326, 328, and330, from access terminals. In FIG. 3, each reverse link transmission isdepicted as being a block, i.e. a group of contiguous OFDM symbols. Itshould be noted that symbol rate hopping, e.g. non contiguous symbolblocks may also be utilized.

In addition, each reverse link frame 308 may include one more reverselink control channels 340, which may include feedback channels; pilotchannels for reverse link channel estimation, and acknowledgmentchannels that may be included in the reverse link transmissions 312-330.Each of the reverse link control channels 340 may include informationfor functions related to, for example, forward link and reverse linkresource requests by each access terminal; channel information, e.g.channel quality information (CQI) for different types of transmission;and pilots from the access terminals that may be used by the accesspoint for channel estimation purposes. It should be noted that more orfewer of such functions may be supported in control channels 340 of oneor all of the carriers. Also, the reverse link control channels 340 mayhop in each frame according to hopping sequences that are the same ordifferent from hopping sequences assigned to data channels.

In certain aspects, to multiplex users on the reverse link controlchannels 340 one or more orthogonal codes, scrambling sequences, or thelike may be utilized to separate each user and/or different types ofinformation transmitted in the reverse link control channels 340. Theseorthogonal codes may be user specific or may be allocated by the accesspoint to each access terminal per communication session or shorterperiod, e.g. per superframe.

In some aspects, some users are assigned to a single carrier so that allof their forward link transmissions for a superframe or multiple framesof a superframe are assigned to the same carrier. That way an accessterminal that is capable of only demodulating a portion of bandwidth atany given time may monitor only a subset of the bandwidth 300, e.g. onecarrier 302 or any number of carrier less than all of the channels. Tosupport such a structure, each of the forward link control channels 306and reverse link control channels 340, for a given carrier, needs tocontain sufficient information so that an access terminal operating onthat carrier 302 may be supported by the channels provided in thesuperframe preamble and forward link control channels 306 and reverselink control channels 340 of the specific carrier without reference toinformation contained in the other carrier. This may be provided byincluding equivalent channels information in the forward link controlchannels 306 and reverse link control channels 340 of each carrier 302.

In certain aspects, acquisition, assignment, access, request, powercontrol, pilot and reporting channels exist in each of the carriers 302in the superframe preamble and forward link control channels 306 andreverse link control channels 340. However, the actual encoding,transmission rates, message types and timing, resource allocations,overhead messaging, hop patterns and/or sequences, and othertransmission and location parameters may vary from carrier to carrier.The format, transmission rate and hopping information may be signaled orotherwise available to an access terminal. This information may beavailable via separate control channels not associated with a specificcarrier or may be provided via other means.

Some terminals, having a greater capability to demodulate signals, maybe scheduled on two or more carriers within a superframe, in consecutivesuperframes, or during its communication session. These multi-carrieraccess terminals may be able to utilize different carriers for reverselink frames and forward link frames during a communication session orsuperframe, may be scheduled on different carriers in differentsuperframes or during the communication session, or may be scheduledover frames that are substantially synchronous in time on differentcarriers. Such multi-carrier access terminals may be scheduled toprovide load balancing of resources for a given carrier and providestatistical multiplexing gains through out the total bandwidth.

In order to support multi-carrier access terminals operating acrossseveral carriers 302 within a superframe, in consecutive superframes, orduring its communication session several approaches may be provided.Firstly, the multi-carrier access terminals may demodulate thesuperframe preambles and forward link control channels 306 for each ofthe carriers individually. In such a case, all assignments, scheduling,power control and the like would be performed on a carrier by carrierbasis.

Alternatively, a separate control channel may contain the operatingparameters of the different carriers, so that an access terminal mayobtain some or all of the information described above with respect tothe superframe preamble and forward link control channels 306 andreverse link control channels 340 for one or more carriers via thatcontrol channel. Also, this additional control channel may includeinformation as to how to demodulate and decode the different superframepreamble and forward link control channels 306 and reverse link controlchannels 340 for one or more of the carriers. This would allow a userbeing able to decode the superframe preamble and forward link controlchannels 306 and reverse link control channels 340 of each carrier atany time.

Further, in some aspects all information for all, or groups, of thecarriers may be maintained in the superframe preamble and forward linkcontrol channels 306 and reverse link control channels 340 of a singleone of the carriers. In such a case, an access terminal capable ofutilizing multiple-carriers in a communication session may tune toreceive control information in a single carrier and transmit its controlinformation in a single carrier. These carriers need not be the same.The carriers utilized for this functionality may vary over timeaccording to a predetermined sequence or some other means.

In addition, for the purposes of scheduling, an assignment mayconstitute multiple assignments from different carriers. That is, anaccess terminal may receive individual assignments on each carrier andthen combine those assignments to determine its assignment for framesthat may or may not overlap, fully or partially, in terms of time forboth the forward and reverse links.

In certain aspects, each carrier comprises 5 MHz of a 20 MHz bandwidth,with carrier comprising 512 subcarriers. However, other sizes ofbandwidth, subcarriers, and carriers may be utilized. Further, thenumber of subcarriers allocated to each carrier may vary, so that thenumber of subcarriers in each carrier may be different from each othercarrier or one carrier may have more subcarriers than the othercarriers. Also, it should be noted that one or more carriers may beasynchronous with respect to each other, e.g. having different start andend times for their forward link frame and/or reverse link frame.Signaling or assignment messages, in the control channel 306 orsuperframe preamble may communicate the timing information in such casesfor that carrier.

Additionally, in certain aspects, some of the available subcarriers inan OFDM symbol in a carrier may be designated as guard subcarriers andmay not be modulated, i.e., no energy is transmitted on thesesubcarriers. The number of guard subcarriers in the superframe preambleand in each frame may be provided via one or more messages in thecontrol channels 306 or superframe preamble.

Further, in some aspects, in order to reduce overhead transmission to aparticular multi-carrier terminal, a packet may be jointly encoded forthat access terminal, even if the symbols of the packets are to betransmitted over subarriers of different carriers. In this way a singlecyclic redundancy check may be utilized for the packet and thetransmissions on some carriers that include symbols from these packetsare not subject to overhead transmissions of cyclic redundancy checks.Alternatively, the access point may modulate its packets on a percarrier basis, i.e. only those symbols to be transmitted on a samecarrier being included in a same packet. Further, it may lump certaincarriers together for the purposes of packet modulation, e.g. onlymodulate symbols from the top two carriers together in a single packet.

It should be noted that a scheduler for each of the carriers may utilizethe same or different approach to hopping, e.g. using different channeltrees or hop permutations, for each carrier. Further, each carrier maybe scheduled according to the same or different techniques andalgorithms. For example, each carrier may include channel trees andstructures as described in co-pending U.S. patent application Ser. No.11/261,837, filed on even date herewith which is incorporated herein byreference in its entirety.

Referring to FIG. 4A, aspects of a forward link frame of a carrier for amultiple access wireless communication system are illustrated. As shownin FIG. 4A, each forward link frame 304 is further divided into twosegments. The first, a control channel 306, which may or may notcomprises a contiguous group of subcarriers, has a variable number ofsubcarriers assigned depending on the desired amount of control data andother considerations. The remaining portions 410 are generally availablefor data transmission. Control channel 306 may include one or more pilotchannels 412 and 414. In symbol rate hopping mode, the pilot channelsmay be present on all of the OFDM symbols in each forward link frame,and need not be included in the control channel 306 in those instances.In both cases, the a signaling channel 416 and the power control channel418 may be present in the control channel 306, as depicted in FIG. 4A.The signaling channel 416 may include assignment, acknowledgement,and/or power references and adjustments for data, control, and pilottransmissions on the reverse link.

Power control channel 418 may carry information regarding interferencegenerated at other sectors due transmissions from access terminals ofthat sector. In certain aspects, power control channel 418 may bepresent on only a single carrier, where all single carrier accessterminals are scheduled on that carrier while multi-carrier accessterminals tune to that carrier for the power control channel 418. Insuch a case, a single power reference may be utilized. Also, in such anaspect, it is possible that multi-carrier access terminals may hop theirreverse link control channel between different frames over time and donot simply transmit reverse link control channel(s) in the same frame(s)as its reverse link data transmissions. In this case, for multi-carrieraccess terminals, a single reference may be utilized to adjust theirtransmission power across all of the carriers allowing for a same powercontrol over all of the carriers for reverse link transmissions by themulti-carrier access terminals.

Alternatively, a multi-carrier access terminal may need to have multiplepower control loops, one for each carrier or a group of carriers havinga common power control channel 418. In this case, transmission on thesingle carrier or grouped carriers would be done on an individual basisand different power references and back-offs may be utilized percarrier.

Also, in certain aspects, the subcarriers 420 at the edge of eachcarrier 302, but often not at the edge of the entire bandwidth, mayfunction as quasi-guard subcarriers. In certain aspects, on the reverselink, these subcarriers 420 are not modulated by access terminals thatare capable of demodulating only one carrier, but may be modulated, onthe reverse link, by access terminals that are capable of demodulatingmultiple carriers, which adds additional bandwidth for transmission tothose access terminals.

On the forward link, in certain aspects, the quasi-guard subcarriers 420are generally not modulated so long as there are some access terminalsin the sector which are not capable of demodulating more than onecarrier. Therefore, in certain aspects, there may be overhead signalingwhether these subcarriers 420 are to be modulated. Further, thequasi-guard subcarriers 420 may or may not be modulated in thesuperframe preamble for the carrier, e.g. they the are not modulatedwhere multiple carriers are utilized by any single user in the system.

It should be noted that where multiple transmit antennas may be used totransmit for a sector, the different transmit antennas should have thesame superframe timing (including the superframe index), OFDM symbolcharacteristics, and hop sequences.

Referring to FIG. 4B, aspects of a reverse link frame of a carrier for amultiple access wireless communication system are illustrated. A pilotchannel 422 may include pilots to allow the access point to estimate thereverse link. A request channel 424 may include information to allow anaccess terminal to request resources for following reverse link, andforward link, frames. In some aspects, a multi-carrier terminal maytransmit on the request channel 424 in only one of the carriers 302.Also, the request channel messages may be repeated on all of thecarriers on which the access terminal may operate during each frame.

A reverse link feedback channel 426 allows access terminals to providefeedback with respect to channel information CQI. The CQI may relate toone or more scheduled modes, or available modes for scheduling, fortransmission to the access terminal. Exemplary modes may includebeamforming, SDMA, precoding, or combinations thereof. A power controlchannel 428 may be used as a reference to allow the access point togenerate power control instructions for reverse link transmission, e.g.data transmissions, by the access terminal. In some aspects, the powercontrol channel 428 may comprise one or more of the feedback channels426.

Data channels 432 may operate according to a symbol rate hopping orblock hopping mode in different reverse link frames 408. Also,quasi-guard subcarriers 440 may be modulated, or not modulated, inaccording to the same rules described with respect to quasi-guardsubcarriers 420 discussed with respect to FIG. 4A.

It should be noted that while FIGS. 4A and 4B depict different channelsthat make up control channels 306 and 340 as being multiplexed in time,this need not be the case. The different channels that make up controlchannels 306 and 340 may multiplexed using different orthogonal,quasi-orthogonal, or scrambling codes, different frequencies, or anycombinations of time, code, and frequency.

While the discussion with respect to FIGS. 2A, 2B, 3, 4A, and 4B includeinformation regarding a superframe preamble, a supeframe preamble neednot be utilized. An alternative approach may include to utilizing frameswith preambles that have equivalent information. Also, a broadcastcontrol channel may be utilized to contain some or all of theinformation of the superframe preamble, with other information containedin a preamble or control channel of a frame.

Referring to FIG. 5, aspects of a method of scheduling users in amulti-carrier system are illustrated. Access terminal operatingparameters, for operating on multiple carriers, are determined, block502. This determination may be made based upon an identification of theaccess terminal, which is transmitted by the access terminal duringinitiation of the communication session. Further, session informationthat is signaled between the access terminal and access point may beutilized to determine this information. Additionally, prior sessioninformation may be utilized. Additionally, a database look-up in acentral server may be performed to obtain the operating parameters basedupon the a device specific identification to the access terminal.

Also, in some aspects, the parameters may be determined by the type oforthogonal or scrambling code utilized by the access terminal tomodulate its access request to initiate its communication session. Insuch a situation, certain orthogonal or scrambling codes utilized formodulating access requests may be reserved for those access terminalsthat may simultaneously operate on two or more carriers.

In further aspects, the parameters may be determined by the number ofcarriers the access terminal transmits the access request to initiateits communication session. Further, the carrier or carriers that areutilized by the access terminal to transmit control information, e.g.CQI information, may be utilized to determine its operating parameterswith respect to the number of carriers on which it can operate.

Then a determination is made whether the access terminal is capable ofoperating, e.g. modulating and/or demodulating, on multiple carrierssimultaneously, block 504. In certain aspects this determination may bemade based upon whether the fast Fourier transform (FFT) capability ofthe access terminal can simultaneously operate on a number ofsubcarriers that is equal or greater than the number of subchannels inone carriers, two carriers, all the way to the total number of carriersavailable in the sector.

As discussed with respect to block 502, the determination may be made ondevice identification or session specific information, or may be madewhere the access terminal operates on multiple carriers, e.g. where theaccess terminal transmits access requests or reverse link controlchannel information across multiple carriers during communication.

Then, if the access terminal is capable of demodulating and/ormodulating multiple carriers simultaneously, it may be scheduled onmultiple carriers, block 508. As discussed above, such scheduling may bemay be, for example, in the form of scheduling an access terminal fordifferent carriers for reverse link frames and forward link frames in asingle superframe, for consecutive superframes, for forward link framesof a single superframe, and/or different reverse link frames of a singlesuperframe.

Alternatively, if the access terminal is not capable of operating onmultiple carriers simultaneously, it may be scheduled on a singlecarrier, block 506. This scheduling may be for multiple consecutivesuperframes or for the entirety of the communication session with thesector.

Referring to FIG. 6, aspects of a method of accessing and communicatingin a wireless communication system is illustrated. An access terminaltunes to one of a plurality of carriers that are available forcommunication, block 600. The identities of the carriers may bepre-provisioned at the access terminal or may signaled via a knownsignaling channel. The access terminal will then demodulate acquisitioninformation transmitted by the access point, block 602. This may forexample be the information in the superframe preamble of the specificcarrier. If this information is properly demodulated by the accessterminal, then an access request is transmitted by the access terminal,block 608.

In certain aspects, the access terminal may modulate its access requestwith an orthogonal or scrambling code that is specific to whether theaccess terminal may operate utilizing one or more than one carriersimultaneously. The orthogonal or scrambling code indicative of theaccess terminal type may be pre-provisioned at the access terminal ormay be signaled via the acquisition information.

In response to the access request, an access grant message is used toacknowledge the access request and assign initial reverse linksubcarriers or block of subcarriers, block 610. In some aspects, theaccess grant may include a timing adjustment for the access terminal toalign its reverse link transmissions with the reverse link timing of theaccess point. The initial assignment may include whether the accessterminal is to operate in a symbol rate or block hopping mode, what arethe subcarriers that are assigned for communication in both the forwardlink and the reverse link, as well as other timing and schedulingparameters. The access terminal will then communicate according to thefirst assignment, block 612.

A second assignment will later be transmitted to the access terminal,block 614. It should be noted that one or more other assignments may betransmitted between the first and second assignment, block 616.Depending on the access terminal capabilities, the second assignment mayinclude a change carrier message and may identify the carrier for whichthe next or current assignment will apply. Alternatively, the changecarrier message may be transmitted prior to, and independently from thesecond assignment or any other assignment. Further, the change carriermessage may be transmitted as one or more data packets in an assignedforward link frame of the access terminal. The one or more data packetsmay be acknowledged by the access terminal, thus reliably indicatingthat the change carrier message has been demodulated. In a furtheraspect, the access grant itself may include change carrier information,either on an initial basis, or on a per carrier basis if each carrier isaccessed separately.

The second assignment, as previously discussed, may include multipleassignments on different carriers that are individually decoded or ajoint assignment for more than one carrier received via a singlecarrier. Also, as previously discussed, this second assignment may beassignment on a single carrier that relates to multiple carriers.

In order to improve operation on newly scheduled carrier's informationregarding timing and other information for that carrier may be provided.If one or more data packets are utilized to signal a change carriermessage, the data packets may include certain parameters for the newcarrier on which the access terminal is being scheduled, thus allowingadditional resources to provide the information for proper communicationon the new carrier. Alternatively, one or all of the superframepreambles or control channels 306 of each carrier may includeinformation to allow communication utilizing the other carriers, or toallow demodulation of the superframe preamble or, possibly, the controlchannels of the other carriers. Additionally, a message, e.g. located inthe control channel 306, directed to the access terminal may betransmitted that includes the parameters for the new carrier.

The access terminal will then communicate according to the secondassignment, block 618. In those cases when the acquisition is notproperly demodulated by the access terminal, the access terminal willtune to another carrier, block 604.

Referring to FIG. 7, a block diagram of an embodiment of a transmittersystem 810 and a receiver system 850 in a MIMO system 800 isillustrated. At transmitter system 810, traffic data for a number ofdata streams is provided from a data source 812 to transmit (TX) dataprocessor 814. In an embodiment, each data stream is transmitted over arespective transmit antenna. TX data processor 814 formats, codes, andinterleaves the traffic data for each data stream based on a particularcoding scheme selected for that data stream to provide coded data.

The coded data for each data stream may be multiplexed with pilot datausing OFDM techniques. The pilot data is typically a known data patternthat is processed in a known manner and may be used at the receiversystem to estimate the channel response. The multiplexed pilot and codeddata for each data stream is then modulated (i.e., symbol mapped) basedon a particular modulation scheme (e.g., BPSK, QSPK, M-PSK, or M-QAM)selected for that data stream to provide modulation symbols. The datarate, coding, and modulation for each data stream may be determined byinstructions performed on provided by processor 830.

The modulation symbols for all data streams are then provided to a TXprocessor 820, which may further process the modulation symbols (e.g.,for OFDM). TX processor 820 then provides N_(T) modulation symbolstreams to N_(T) transmitters (TMTR) 822 a through 822 t. Eachtransmitter 822 receives and processes a respective symbol stream toprovide one or more analog signals, and further conditions (e.g.,amplifies, filters, and upconverts) the analog signals to provide amodulated signal suitable for transmission over the MIMO channel. N_(T)modulated signals from transmitters 822 a through 822 t are thentransmitted from N_(T) antennas 824 a through 824 t, respectively.

At receiver system 850, the transmitted modulated signals are receivedby N_(R) antennas 852 a through 852 r and the received signal from eachantenna 852 is provided to a respective receiver (RCVR) 854. Eachreceiver 854 conditions (e.g., filters, amplifies, and downconverts) arespective received signal, digitizes the conditioned signal to providesamples, and further processes the samples to provide a corresponding“received” symbol stream.

An RX data processor 860 then receives and processes the N_(R) receivedsymbol streams from N_(R) receivers 854 based on a particular receiverprocessing technique to provide N_(T) “detected” symbol streams. Theprocessing by RX data processor 860 is described in further detailbelow. Each detected symbol stream includes symbols that are estimatesof the modulation symbols transmitted for the corresponding data stream.RX data processor 860 then demodulates, deinterleaves, and decodes eachdetected symbol stream to recover the traffic data for the data stream.The processing by RX data processor 818 is complementary to thatperformed by TX processor 820 and TX data processor 814 at transmittersystem 810.

RX data processor 860 may be limited in the number of subcarriers thatit may simultaneously demodulate, e.g. 512 subcarriers or 5 MHz, andsuch a receiver should be scheduled on a single carrier. This limitationmay be a function of its FFT range, e.g. sample rates at which theprocessor 860 may operate, the memory available for FFT, or otherfunctions available for demodulation. Further, the greater the number ofsubcarriers utilized, the greater the expense of the access terminal.

The channel response estimate generated by RX processor 860 may be usedto perform space, space/time processing at the receiver, adjust powerlevels, change modulation rates or schemes, or other actions. RXprocessor 860 may further estimate the signal-to-noise-and-interferenceratios (SNRs) of the detected symbol streams, and possibly other channelcharacteristics, and provides these quantities to a processor 870. RXdata processor 860 or processor 870 may further derive an estimate ofthe “operating” SNR for the system. Processor 870 then provides channelstate information (CSI), which may comprise various types of informationregarding the communication link and/or the received data stream. Forexample, the CSI may comprise only the operating SNR. The CSI is thenprocessed by a TX data processor 878, modulated by a modulator 880,conditioned by transmitters 854 a through 854 r, and transmitted back totransmitter system 810.

At transmitter system 810, the modulated signals from receiver system850 are received by antennas 824, conditioned by receivers 822,demodulated by a demodulator 840, and processed by a RX data processor842 to recover the CSI reported by the receiver system. The reported CSIis then provided to processor 830 and used to (1) determine the datarates and coding and modulation schemes to be used for the data streamsand (2) generate various controls for TX data processor 814 and TXprocessor 820. Alternatively, the CSI may be utilized by processor 870to determine modulation schemes and/or coding rates for transmission,along with other information. This may then be provided to thetransmitter which uses this information, which may be quantized, toprovide later transmissions to the receiver.

Processors 830 and 870 direct the operation at the transmitter andreceiver systems, respectively. Memories 832 and 872 provide storage forprogram codes and data used by processors 830 and 870, respectively.

At the receiver, various processing techniques may be used to processthe N_(R) received signals to detect the N_(T) transmitted symbolstreams. These receiver processing techniques may be grouped into twoprimary categories (i) spatial and space-time receiver processingtechniques (which are also referred to as equalization techniques); and(ii) “successive nulling/equalization and interference cancellation”receiver processing technique (which is also referred to as “successiveinterference cancellation” or “successive cancellation” receiverprocessing technique).

While FIG. 7 discusses a MIMO system, the same system may be applied toa multi-input single-output system where multiple transmit antennas,e.g. those on a base station, transmit one or more symbol streams to asingle antenna device, e.g. a mobile station. Also, a single output tosingle input antenna system may be utilized in the same manner asdescribed with respect to FIG. 7.

The transmission techniques described herein may be implemented byvarious means. For example, these techniques may be implemented inhardware, firmware, software, or a combination thereof. For a hardwareimplementation, the processing units at a transmitter may be implementedwithin one or more application specific integrated circuits (ASICs),digital signal processors (DSPs), digital signal processing devices(DSPDs), programmable logic devices (PLDs), field programmable gatearrays (FPGAs), processors, controllers, micro-controllers,microprocessors, electronic devices, other electronic units designed toperform the functions described herein, or a combination thereof. Theprocessing units at a receiver may also be implemented within one ormore ASICs, DSPs, processors, and so on.

For a software implementation, the transmission techniques may beimplemented with modules (e.g., procedures, functions, and so on) thatperform the functions described herein. The software codes may be storedin a memory (e.g., memory 830, 872 x or 872 y in FIG. 7) and executed bya processor (e.g., processor 832, 870 x or 870 y). The memory may beimplemented within the processor or external to the processor.

It should be noted that the concept of channels herein refers toinformation or transmission types that may be transmitted by the accesspoint or access terminal. It does not require or utilize fixed orpredetermined blocks of subcarriers, time periods, or other resourcesdedicated to such transmissions.

The previous description of the disclosed embodiments is provided toenable any person skilled in the art to make or use the presentinvention. Various modifications to these embodiments will be readilyapparent to those skilled in the art, and the generic principles definedherein may be applied to other embodiments without departing from thespirit or scope of the invention. Thus, the present invention is notintended to be limited to the embodiments shown herein but is to beaccorded the widest scope consistent with the principles and novelfeatures disclosed herein.

The invention claimed is:
 1. A wireless communication apparatus,comprising: a memory storing program codes and data; and a processorcoupled with the memory and operable by using the program codes anddata, the processor configured to: receive a plurality of communicationsrespectively from a plurality of wireless access terminals; in responseto said communications, make respectively associated determinationsregarding whether the respectively associated wireless access terminalsare capable of operating on more than one carrier simultaneously; assignat least one carrier to each said wireless access terminal based on saiddeterminations; and instruct control channel transmissions,respectively, on the assigned carriers; wherein the control channeltransmission on at least one of the assigned carriers permits theassociated wireless access terminal to communicate within the at leastone assigned carrier without utilizing information contained in anyother control channel transmissions.
 2. The wireless communicationapparatus of claim 1 wherein the processor is further configured toinstruct that the control channel transmissions occur synchronously. 3.The wireless communication apparatus of claim 1, wherein the processoris further configured to instruct that the control channel transmissionsoccur asynchronously.
 4. The wireless communication apparatus of claim1, wherein the processor is further configured to instruct transmissionof a superframe preamble prior to the control channel transmissions, andwherein the superframe preamble spans each of the assigned carriers. 5.The wireless communication apparatus of claim 1, wherein the processoris further configured to instruct, for each of the assigned carriers,transmission of a superframe preamble prior to the control channeltransmission.
 6. A method of wireless communication, comprising:receiving a plurality of communications respectively from a plurality ofwireless access terminals; in response to said communications, makingrespectively associated determinations regarding whether therespectively associated wireless access terminals are capable ofoperating on more than one carrier simultaneously; assigning at leastone carrier to each said wireless access terminal based on saiddeterminations; and instructing control channel transmissions,respectively, on the assigned carriers; wherein the control channeltransmission on at least one of the assigned carriers permits theassociated wireless access terminal to communicate within the at leastone assigned carrier without utilizing information contained in anyother control channel transmissions.
 7. The method of claim 6, whereinthe control channel transmissions are synchronous.
 8. The method ofclaim 6, wherein the control channel transmissions are asynchronous. 9.The method of claim 6, including instructing transmission of asuperframe preamble prior to the control channel transmissions, whereinthe superframe preamble spans each of the assigned carriers.
 10. Themethod of claim 6, including instructing, for each of the assignedcarriers, transmission of a superframe preamble prior to the controlchannel transmission.
 11. A wireless communication apparatus,comprising: means for receiving a plurality of communicationsrespectively from a plurality of wireless access terminals; means formaking, in response to said communications, respectively associateddeterminations regarding whether the respectively associated wirelessaccess terminals are capable of operating on more than one carriersimultaneously; means for assigning at least one carrier to each saidwireless access terminal based on said determinations; and means forinstructing control channel transmissions, respectively, on the assignedcarriers; wherein the control channel transmission on at least one ofthe assigned carriers permits the associated wireless access terminal tocommunicate within the at least one assigned carrier without utilizinginformation contained in any other control channel transmissions. 12.The wireless communication apparatus of claim 11, wherein the controlchannel transmissions are synchronous.
 13. The wireless communicationapparatus of claim 11, wherein the control channel transmissions areasynchronous.
 14. The wireless communication apparatus of claim 11,including means for instructing transmission of a superframe preambleprior to the control channel transmissions, wherein the superframepreamble spans each of the assigned carriers.
 15. The wirelesscommunication apparatus of claim 11, including means for instructing,for each of the assigned carriers, transmission of a superframe preambleprior to the control channel transmission.
 16. A non-transitorycomputer-readable medium, comprising: code for causing at least oneprocessor to: receive a plurality of communications respectively from aplurality of wireless access terminals; in response to saidcommunications, make respectively associated determinations regardingwhether the respectively associated wireless access terminals arecapable of operating on more than one carrier simultaneously; assign atleast one carrier to each said wireless access terminal based on saiddeterminations; and instruct control channel transmissions,respectively, on the assigned carriers; wherein the control channeltransmission on at least one of the assigned carriers permits theassociated wireless access terminal to communicate within the at leastone assigned carrier without utilizing information contained in anyother control channel transmissions.
 17. The non-transitorycomputer-readable medium of claim 16, wherein the control channeltransmissions are synchronous.
 18. The non-transitory computer-readablemedium of claim 16, wherein the control channel transmissions areasynchronous.
 19. The non-transitory computer-readable medium of claim16, wherein the non-transitory computer-readable medium furthercomprises code for causing at least one processor to instructtransmission of a superframe preamble prior to the control channeltransmissions, wherein the superframe preamble spans each of theassigned carriers.
 20. The non-transitory computer-readable medium ofclaim 16, wherein the non-transitory computer-readable medium furthercomprises code for causing at least one processor to instruct, for eachof the assigned carriers, transmission of a superframe preamble prior tothe control channel transmission.